Cervical Spinal Cord Morphometrics in Degenerative Cervical Myelopathy: Quantification using Semi-automated Normalized Technique and Correlation with Neurological Dysfunctions.

BACKGROUND CONTEXT: Degenerative cervical myelopathy (DCM) is characterized by spinal cord atrophy. Accurate estimation of spinal cord atrophy is key to the understanding of neurological diseases, including DCM. However, its clinical application is hampered by difficulties in its precise and consistent estimation due to significant variability in spinal cord morphometry along the cervical spine, both within and between individuals. PURPOSE: To characterize morphometrics of the compressed spinal cord in DCM patients. We employed our semi-automated analysis framework that incorporates the Spinal Cord Toolbox (SCT) and a normalization approach to effectively address the challenges posed by cord compression in these patients. Additionally, we examined the clinical relevance of these morphometric measures to enhance our understanding of DCM pathophysiology. STUDY DESIGN: Prospective study. PATIENT SAMPLE: This study investigated 36 DCM patients and 31 healthy controls (HCs). OUTCOME MEASURES: Clinical scores including 9-hole peg test for hand dexterity, hand grip strength, balance, gait speed, modified Japanese Orthopaedic Association (mJOA) score, and imaging-based spinal cord morphometrics. METHOD: Using the generic spine acquisition protocol and our semi-automated analysis pipeline, spinal cord morphometrics, including cross-sectional area (CSA), anterior-posterior (AP) and transverse (RL) diameters, eccentricity, and solidity, were estimated from sagittal T2w magnetic resonance imaging (MRI) images using the Spinal Cord Toolbox (SCT). Normalized metrics were extracted from the C1 to C7 vertebral levels and compared between DCM patients and HC. Morphometric data at regions of maximum spinal cord compression (MSCC) were correlated with the clinical scores. A subset of participants underwent follow-up scans at six months to monitor longitudinal changes in spinal cord atrophy. RESULTS: Spinal cord morphometric data were normalized against the healthy population morphometry (PAM50 database) and extracted for all participants. DCM patients showed a notable reduction in CSA, AP, and RL diameter across all vertebral levels compared to HC. MSCC metrics correlated significantly with clinical scores like dexterity, grip strength, and mJOA scores. Longitudinal analysis indicated a decrease in CSA and worsening clinical scores in DCM patients. CONCLUSION: Our processing pipeline offers a reliable method for assessing spinal cord compression in DCM patients. Normalized spinal cord morphometrics, particularly the CSA could have potential for monitoring DCM disease severity and progression, guiding treatment decisions. Furthermore, to our knowledge our study is the first to apply the generic spinal cord acquisition protocol, ensuring consistent imaging across different MRI scanners and settings. Coupled with our semi-automated analysis pipeline, this protocol is key for the detailed morphometric characterization of compressed spinal cords in patients with DCM, a disease that is both complex and heterogenous. This study was funded by the National Institute of Neurological Disorders and Stroke (NINDS) (K23:NS091430) and (R01: NS129852-01A1).

Basilar Impression: A Systematic Review and Meta-Analysis of Clinical Features, Operative Strategies, and Outcomes.

OBJECTIVE: Basilar impression (BI) is a rare yet debilitating abnormality of the craniovertebral junction, known to cause life-threatening medullary brainstem compression. Our study analyzes surgical approaches for BI and related outcomes. METHODS: A systematic review was conducted using PubMed, Google Scholar, and Web of Science electronic databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines to critically assess primary articles examining BI. RESULTS: We analyzed 87 patients from 65 articles, mostly female (55.17%) with a mean age of 46.31 ± 17.94 years, commonly presenting with motor (59.77%) and sensory deficits (55.17%). Commonly employed procedures included posterior occipitocervical fusion (24.14%), anterior decompression (20.69%), and combined anterior decompression with posterior fusion (21.84%). Patients who underwent anterior approaches were found to be older (55.38 ± 17.67 vs. 45.49 ± 18.78 years, P < 0.05) and had a longer duration from symptom onset to surgery (57.39 ± 64.33 vs. 26.02 ± 29.60 months, P < 0.05) compared to posterior approaches. Our analysis revealed a significant association between a longer duration from symptom onset to surgery and an increased likelihood of undergoing odontoidectomy and decompression (odds ratio: 1.02, 95% confidence interval: 1.00-1.03, P < 0.05). Furthermore, after adjusting for all other covariates, a history of rheumatoid arthritis and the use of a posterior approach were significantly associated with an elevated risk of postoperative complications (P < 0.05). CONCLUSIONS: The treatment approach to complex craniovertebral junction disease should be tailored to the surgeon's experience and the nature of the compressive pathology.

Age is Associated with Level of First-Time Anterior Cervical Discectomy and Fusion: An Ordinal Analysis of Factors Influencing Timing of Cervical Degeneration.

BACKGROUND: Symptomatic cervical spondylosis is often treated with anterior cervical discectomy and fusion (ACDF). However, few factors can predict which cervical level will degenerate and require intervention. This analysis evaluates preprocedural factors associated with level of first-time single-level ACDF. METHODS: We performed a retrospective analysis of patients who underwent single-level ACDF without prior history of spine surgery. Mann Whitney U-tests and Spearman rank-order correlation were performed for analyses of associations between variables of interest and ACDF level. Adjusted odds-ratios were calculated by proportional-odds logistic regression, with age, sex, body mass index, current tobacco use, history of neck trauma, preoperative radicular symptoms, and preoperative myelopathic symptoms as covariates. RESULTS: One hundred forty-one patients met inclusion criteria, and age demonstrated a negative correlation with ACDF level, such that younger patients tended to have ACDF performed at inferior subaxial levels (P = 0.0006, rho = -0.31, moderately strong relationship). Patients with preoperative radicular symptoms and myelopathic symptoms were more likely to have ACDF performed at inferior (P = 0.0001) and superior (P < 0.0001) levels, respectively. Patient sex, body mass index, current tobacco use, and history of neck trauma were not predictive of ACDF level. When adjusting for the above variables in a proportional-odds ordinal logistic regression model, a one-year increase in age conferred a 4% increase in the odds of requiring an ACDF at a given superior level compared to the adjacent inferior level. CONCLUSIONS: Age is correlated with level of first-time single level ACDF. Individual subaxial levels may have unique biomechanical properties that influence degeneration.

3D-Printed Spine Models for Planning Staged Minimally Invasive Transverse Process Resections for Bertolotti Syndrome: Technical Note.

Background: Three-dimensional (3D) printing has enabled numerous advances in spine surgery execution and education. However, few examples exist to outline how this technology can aid the performance of complex spine surgery using minimally invasive surgery (MIS) techniques. Therefore, we present a case that illustrates the benefits of 3D-printed spine model production before and after correction of a congenital lumbosacral anomaly using an MIS approach. Case Report: A 40-year-old woman with Bertolotti syndrome underwent a staged bilateral L6 MIS transverse process resection for the treatment of severe and progressive axial back pain which had repeatedly failed conservative management. 3D-printed spine models were used for pre- and post-operative surgical planning and patient counseling. Conclusion: 3D-printed spine models can aid in the planning of complex spine cases suited for an MIS approach.

Single Nucleotide Polymorphisms and Adolescent Idiopathic Scoliosis: A Systematic Review and Meta-Analysis of the Literature.

STUDY DESIGN: Meta-analysis. OBJECTIVE: To determine the single nucleotide polymorphisms (SNPs) that are related to adult idiopathic scoliosis. SUMMARY AND BACKGROUND DATA: Adolescent idiopathic scoliosis (AIS) is considered one of the most prevalent spinal diseases. Even though the cause of AIS is yet to be determined, family history and sex have shown conclusive associations. Multiple studies have indicated that AIS is more prevalent in families where at least one other first-degree relative is similarly affected, indicating a possible genetic etiology to AIS. MATERIALS AND METHODS: Articles were collected from 3 different search engines and then processed in 2 stages for final article selection for quantitative analysis. Five different genetic models were represented to show the association between the different SNPs and AIS. The Hardy-Weinberg equilibrium was examined using Fisher exact test, with significance set at P <0.05. The final analysis paper's quality was evaluated using the Newcastle Ottawa Scale. Kappa interrater agreement was calculated to evaluate the agreement between authors. RESULTS: The final analysis comprised 43 publications, 19412 cases, 22005 controls, and 25 distinct genes. LBX1 rs11190870 T>C and MATN-1 SNPs were associated with an increased risk of AIS in one or all of the 5 genetic models. IGF-1 , estrogen receptor alfa, and MTNR1B , SNPs were not associated with AIS in all 5 genetic models. Newcastle Ottawa Scale showed good quality for the selected articles. Cohen k = 0.741 and Kappa interrater agreement of 84% showed that the writers were in strong agreement. CONCLUSIONS: There seem to be associations between AIS and genetic SNP. Further larger studies should be conducted to validate the results.

Image-Guided Percutaneous Multilevel Pediculosynthesis for Treatment of Contiguous Pedicle Stress Fractures: Technical Case Report.

BACKGROUND: Nontraumatic pedicle fracture is uncommon, with sparsely described cases of conservative management versus surgical treatment by open fusion or percutaneous fixation. METHODS: We report the case of a 60-year-old woman with nontraumatic L4 and L5 pedicle fracture who developed additional pedicle fractures at L3 while undergoing conservative management in a brace. The patient underwent percutaneous pediculosynthesis with screw fixation without fusion at L3-5 bilaterally. RESULTS: The treatment led to fracture healing with good radiographic result and resolution of her symptoms. CONCLUSIONS: A trial of conservative management is typically warranted in most cases of nontraumatic pedicle fracture, but there is risk of refractory or progressive symptoms and subsequent fracture. Minimally invasive fixation is a viable surgical option that can be used in multilevel fractures.

Applying 3-Dimensional Printing and Modeling for Preoperative Reconstruction and Instrumentation Placement Planning in Complex Deformity Surgery.

BACKGROUND: Advances in three-dimensional (3D) printing technology have enabled the development of customized instrumentation and surgical training platforms. However, no existing studies have assessed how patient-specific 3D-printed spine models can facilitate patient education and operative planning in complex spinal deformity correction. OBJECTIVE: To present a cost-effective technique for constructing personalized 3D-printed spine models for patients with severe spinal deformities and to outline how these models can promote informed consent, trainee education, and planning for instrumentation placement and alignment correction. METHODS: We present 2 patients who underwent surgical correction of progressive thoracolumbar deformities. Full-scale 3D-printed models of each patient's spine were produced preoperatively and used during clinic evaluations, surgical planning, and as intraoperative references. RESULTS: Each model took 9 days to build and required less than 60 US dollars of material costs. Both patients were treated with a posterior approach and contiguous multilevel osteotomies. Postoperatively, their alignment parameters and neurological deficits improved. CONCLUSION: Personalized 3D-printed spine models can aid in patient education, surgical training, visualization, and correction of complex spinal deformities.

Open Paddle Lead Trial for Spinal Cord Stimulation: An Institutional Experience.

BACKGROUND: Spinal cord stimulation (SCS) is an accepted treatment for certain chronic pain syndromes. It is imperative that patients undergo a stimulation screening trial. For trial stimulation, typically patients undergo a percutaneous lead placement. Due to technical considerations, there exists a subset of patients who are not candidates for a percutaneous trial. OBJECTIVE: We present our experience with open paddle trial for spinal cord stimulation and review the characteristics of this patient population as well as the technique and efficacy of an open paddle lead trial for spinal cord stimulation. STUDY DESIGN: Retrospective review. SETTING: University of Texas Southwestern Medical Center, Department of Neurosurgery. METHODS: We retrospectively identified 25 patients undergoing a paddle lead trial for spinal cord stimulation from September 2014 to September 2019. RESULTS: Twenty-five patients underwent a paddle lead trial for spinal cord stimulation. The average age was 61 with a range of 40 to 82 years; 19 were women and 6 were men. Twenty-two patients (88%) had failed back surgery syndrome (FBSS). Nine patients had attempted percutaneous trials that were unsuccessful, and 14 patients had extensive hardware and/or scar tissue, necessitating an open paddle trial. Twenty-three (92%) patients had a positive trial and went on to permanent implantation. LIMITATIONS: The retrospective nature is a major limitation as well as loss to follow-up on several patients. CONCLUSION: Patients, who have either failed or are deemed suboptimal for percutaneous trialing for spinal cord stimulation, should be considered for open paddle lead trialing. A multidisciplinary approach improves communication and helps to identify that subset of patients who otherwise may be left to pursue conservative measures only.

Transfusion Guidelines in Traumatic Brain Injury: A Systematic Review and Meta-Analysis of the Currently Available Evidence.

Our study aims to provide a synthesis of the best available evidence on the hemoglobin (hgb) red blood cell (RBC) transfusion thresholds in adult traumatic brain injury (TBI) patients, as well as describing the risk factors and outcomes associated with RBC transfusion in this population. A systematic review and meta-analysis was conducted using PubMed, Google Scholar, and Web of Science electronic databases according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines to assess articles discussing RBC transfusion thresholds and describe complications secondary to transfusion in adult TBI patients in the perioperative period. Fifteen articles met search criteria and were reviewed for analysis. Compared to non-transfused, TBI patients who received transfusion tended to be primarily male patients with worse Injury Severity Score (ISS) and Glasgow Coma Scale. Further, the meta-analysis corroborated that transfused TBI patients are older (p = 0.04), have worse ISS scores (p = 0.001), receive more units of RBCs (p = 0.02), and have both higher mortality (p < 0.001) and complication rates (p < 0.0001). There were no differences identified in rates of hypertension, diabetes mellitus, and Abbreviated Injury Scale scores. Additionally, whereas many studies support restrictive (hgb <7 g/dL) transfusion thresholds over liberal (hgb <10 g/dL), our meta-analysis revealed no significant difference in mortality between those thresholds (p = 0.79). Current Class B/C level III evidence predominantly recommends against a liberal transfusion threshold of 10 g/dL for TBI patients (Class B/C level III), but our meta-analysis found no difference in survival between groups. There is evidence suggesting that an intermediate threshold between 7 and 9 g/dL, reflecting the physiological oxygen needs of cerebral tissue, may be worth exploring.

Effect of Zeolite-Y Modification on Crude-Oil Direct Hydrocracking.

To study the role of modified zeolite-Y-based hydrocracking catalyst in crude-oil hydroconversion, various hydrocracking catalysts were synthesized with various zeolites. The zeolites and catalysts were characterized with nitrogen adsorption (N2-adsorption), small-angle X-ray scattering, X-ray powder diffraction (XRD), wavelength-dispersive X-ray fluorescence, and the ammonia temperature-programmed desorption (NH3-TPD). Their reaction performance was evaluated with crude oil under commercial hydrocracker operating conditions in a pilot plant unit. The results showed that the catalysts with high acidity, strong acid sites, and mesopores can enhance the crude conversion. The acidity and mesoporosity of the zeolite and the catalysts play critical roles in determining the catalyst performance.

The Clinical Use of Serum Biomarkers in Traumatic Brain Injury: A Systematic Review Stratified by Injury Severity.

BACKGROUND: Serum biomarkers have gained significant popularity as an adjunctive measure in the evaluation and prognostication of traumatic brain injury (TBI). However, a concise and clinically oriented report of the major markers in function of TBI severity is lacking. This systematic review aims to report current data on the diagnostic and prognostic utility of blood-based biomarkers across the spectrum of TBI. METHODS: A literature search of the PubMed/Medline electronic database was performed according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. We excluded systematic reviews and meta-analyses that did not provide novel data. The American College of Cardiology/American Heart Association criteria were used to assess levels of evidence. RESULTS: An initial 1463 studies were identified. In total, 115 full-text articles reporting on 94 distinct biomarkers met the inclusion criteria. Glasgow Coma Scale scores, computed tomography/magnetic resonance imaging abnormalities, and injury severity scores were the most used clinical diagnostic variables. Glasgow Outcome Scores and 1-, 3-, and 6-month mortality were the most used clinical prognostic variables. Several biomarkers significantly correlated with these variables and had statistically significant different levels in TBI subjects when compared with healthy, orthopedic, and polytrauma controls. The biomarkers also displayed significant variability across mild, moderate, and severe TBI categories, as well as in concussion cases. CONCLUSIONS: This review summarizes existing high-quality evidence that supports the use of severity-specific biomarkers in the diagnostic and prognostic evaluation of TBI. These data can be used as a launching platform for the validation of upcoming clinical studies.

Anticoagulation in Elective Spine Cases: Rates of Hematomas Versus Thromboembolic Disease.

STUDY DESIGN: Retrospective cohort study with propensity matched cohorts. OBJECTIVE: The purpose of this study was to evaluate the association of anticoagulation with VTE and hematoma complications after spine surgery. SUMMARY OF BACKGROUND DATA: One of the major complications of surgery is VTE which can range in presentation. Spine surgery is an especially complex balance between minimizing the risk of a VTE event and also the increased risk of a hematoma which can lead to devastating neurological outcomes. METHODS: The elective spine surgery cases at a single academic center between 2015 and 2017 were identified. A total of 3790 patients were initially identified. Two hundred sixty patients were excluded. The cohort was then matched using a propensity score. This matched a single patient who did not receive anticoagulation to a single patient who did within the institution. This left a total of 1776 patients with 888 patients in each arm. RESULTS: The incidence of VTE, PE, and unplanned reoperation for hematoma in this cohort was 0.96%, 0.34%, and 1.13%, respectively. Predicted odds of VTE and PE were not significantly different; however, the odds of an unplanned reoperation for hematoma (odds ratio [OR] = 7.535, 95% confidence interval [CI]: 2.004-28.340, P = 0.002) were greater for those who received pharmacological anticoagulation in our institutional cohort. CONCLUSION: In this study, anticoagulation does not lead to lower rates of VTE events, but it increases the risk of symptomatic hematomas which require a return trip to the OR. While this was not a randomized controlled trial, we attempted to correct for this with propensity matching. Future randomized control trials would be needed.Level of Evidence: 3.

Compressive Cervical Myelopathy in Patients With Demyelinating Disease of the Central Nervous System: Improvement After Surgery Despite a Late Diagnosis.

Objective We aimed to assess the impact of surgical intervention on outcome in patients diagnosed with demyelinating disorders and cervical degenerative disease warranting surgical intervention. Methods The records of patients with a diagnosis of a demyelinating disorder of the central nervous system who underwent cervical spine surgery at a single institution from 2016 to 2020 were reviewed. Demyelinating disease included multiple sclerosis (MS), neuromyelitis optica, and transverse myelitis (TM). The dates of initial spine symptom onset, recognition of spinal pathology by the primary provider, referral to spine surgery, and spine surgery procedures were collected. Hospital length of stay (LOS) and postoperative outcomes and complications were recorded. Results A total of 19 patients with a diagnosis of demyelinating disorders underwent cervical spine surgery at our institution. Seventeen patients had MS. The average time interval between a documented diagnosis of myelopathy or radiculopathy and referral to the Spine clinic was 67.95 months (M=40, SD=64.87). Twelve patients had imaging studies depicting degenerative spine disease that would warrant surgical intervention at the time of examination by their primary physician. The average delay for referral to the Spine clinic for these patients was 16.5 months (M=5; SD=25.36). More than 89% of patients experienced significant neurologic improvement postoperatively. Conclusions There is a delay in the recognition of cervical spine disease amenable to a surgical resolution in patients with demyelinating disorders. Surgical treatment can lead to significant clinical improvement in this patient population even if delayed, and likely carries similar risk to that of the general population.

Bertolotti Syndrome With Articulated L5 Transverse Process Causing Intractable Back Pain: Surgical Video Showcasing a Minimally Invasive Approach for Disconnection: 2-Dimensional Operative Video.

Bertolotti syndrome is a commonly missed cause of intractable back pain that affects 4% to 8% of the general population. It involves the congenital malformation of a transitional lumbosacral vertebra, with total or partial and unilateral or bilateral transverse process (TP) fusion or articulation to the sacrum. The pain can be debilitating, and the tethering of the spine to the sacrum can encourage deformity formation in the coronal plane and lead to early degenerative changes, especially if present only unilaterally. We present the case of a 24-yr-old woman with no notable prior medical history who presented with years of lower axial back pain radiating to her thighs, which limited her activities of daily living and was resistant to conservative management. Her imaging showed an abnormally large left L5 TP, which was articulated to the sacrum, and signs of early coronal deformity. She had responded almost completely to repeated steroid injections into the TP-sacral joint, but that effect was very transient. Informed patient consent was obtained prior to her surgery. She underwent a minimally invasive tube disconnection of the abnormal joint with partial distal resection of the TP, and her symptoms completely resolved. This case highlights the importance of correlating clinical symptoms with aberrant anatomy, and the role of selective surgery in providing symptomatic relief. This case report was written in compliance with our institutional ethical review board approval, and patient consent was waived in light of the retrospective and deidentified nature of the data presented in accordance with the University of Texas Southwestern institutional review board.

Electronic Communication Patterns Could Reflect Preoperative Anxiety and Serve as an Early Complication Warning in Elective Spine Surgery Patients with Affective Disorders: A Retrospective Analysis of a Cohort of 1199 Elective Spine Patients.

OBJECTIVE: The analysis of perioperative electronic patient portal (EPP) communication may provide risk stratification and insight for complication prevention in patients with affective disorders (ADs). We aimed to understand how patterns of EPP communication in patients with AD relate to preoperative narcotic use, surgical outcomes, and readmission rates. METHODS: The records of adult patients who underwent elective spinal surgery between January 2010 and August 2017 at a single institution were retrospectively reviewed for analysis. Primary outcomes included preoperative narcotic use, the number of perioperative EPP messages sent, rates of perioperative complications, hospital length of stay, emergency department (ED) visits within 6 weeks, and readmissions within 30 days after surgery. RESULTS: A total of 1199 patients were included in the analysis. Patients with an AD were more likely to take narcotics before surgery (51.69% vs. 41%, P < 0.001) and to have active EPP accounts (75.36% vs. 69.75%, P = 0.014) compared with controls. They were also more likely to send postoperative messages (38.89% vs. 32.75%, P = 0.030) and tended to send more messages (0.67 vs. 0.48, P = 0.034). The AD group had higher rates of postoperative complications (8.21% vs. 3.98%, P = 0.001), ED visits (4.99% vs. 2.43%, P = 0.009), and readmissions postoperatively (2.49% vs. 1.38%, P = 0.049). CONCLUSIONS: AD patients have specific patterns of perioperative EPP communication. They are at a higher risk of postoperative complications. Addressing these concerns early may prevent more serious morbidity and avoid unnecessary ED visits and readmissions, thus reducing costs and improving patient care.

Traumatic Lumbar Interdural Cyst with Intradural Expansion and Compression of the Cauda Equina: Case Report and Surgical Video.

Intradural arachnoid cysts are common entities that can be congenital, or caused by infectious, inflammatory, or even traumatic processes. However, true "inter"-dural cysts formed between the two lamellae of the lumbar dura without any fistulous arachnoid connection are rare. We present the case of a post-traumatic interdural cyst formation of the lumbar spine that compressed the roots of the cauda equina causing acute unrelenting pain. The cyst walls were formed by the true dural layers, and the cavity was filled with blood degradation products without any arachnoid connection to the subdural space. A commented video that details the diagnostic and surgical aspects of this case, alongside intraoperative footage is provided.

Pseudomeningocele and percutaneous intrathecal lead placement complication for spinal cord stimulator.

The incidence of symptomatic percutaneous intrathecal subarachnoid lead placement for spinal cord stimulator is almost an unheard of complication in the literature. We present the first case of a spinal cord stimulator implant with a complication of symptomatic intrathecal subarachnoid lead placement with a pseudomeningocele. This complication was found with myelogram and addressed by replacement with a new spinal cord stimulator implant with paddle leads instead of percutaneous leads and obliterating the pseudomeningocele tract. Technique for epidural lead placement is discussed. This case illustrates a spinal cord stimulator implant complication of intrathecal percutaneous lead placement with pseudomeningocele and its recognition and treatment involving replacement of the system while minimizing risk of postoperative cerebrospinal fluid leakage. Intraoperative neuromonitoring and interrogation of the spinal cord stimulator system during implantation are effective tools for accurate epidural lead placement.

Intraneural Posterior Interosseous Nerve Lipoma with Complete Paralysis: Case Report and Review of the Literature.

An intraneural posterior interosseous nerve (PIN) lipoma is a rare entity consisting of two types and only two previously reported cases. Treatment involves total excision for the well-encapsulated "true intraneural lipomas" type and subtotal resection for the other type, fibrolipomatous hamartomas of the nerve. We present the management and surgical treatment of a case that illustrates a variation of the traditional posterolateral surgical approach for the complete excision of an intraneural PIN lipoma-contrary to the more commonly used anterior approach in literature-along with a literature review of intraneural PIN lipomas.